1Pervasives(3) OCaml library Pervasives(3)
2
6 Pervasives - The initially opened module.
7
9 Module Pervasives
10
12 Module Pervasives
13 : sig end
14 The initially opened module.
17 This module provides the basic operations over the built-in types (num‐
19 bers, booleans, strings, exceptions, references, lists, arrays,
20 input-output channels, ...)
21 This module is automatically opened at the beginning of each compila‐
23 tion. All components of this module can therefore be referred by their
24 short name, without prefixing them by Pervasives .
25 === Exceptions ===
34 val raise : exn -> 'a
37 Raise the given exception value
39 val invalid_arg : string -> 'a
44 Raise exception Invalid_argument with the given string.
46 val failwith : string -> 'a
51 Raise exception Failure with the given string.
53 exception Exit
58 The Exit exception is not raised by any library function. It is pro‐
61 vided for use in your programs.
62 === Comparisons ===
68 val (=) : 'a -> 'a -> bool
71 e1 = e2 tests for structural equality of e1 and e2 . Mutable struc‐
74 tures (e.g. references and arrays) are equal if and only if their cur‐
75 rent contents are structurally equal, even if the two mutable objects
76 are not the same physical object. Equality between functional values
77 raises Invalid_argument . Equality between cyclic data structures may
78 not terminate.
79 val (<>) : 'a -> 'a -> bool
84 Negation of Pervasives.(=) .
86 val (<) : 'a -> 'a -> bool
91 See Pervasives.(>=) .
93 val (>) : 'a -> 'a -> bool
98 See Pervasives.(>=) .
100 val (<=) : 'a -> 'a -> bool
105 See Pervasives.(>=) .
107 val (>=) : 'a -> 'a -> bool
112 Structural ordering functions. These functions coincide with the usual
114 orderings over integers, characters, strings and floating-point num‐
115 bers, and extend them to a total ordering over all types. The ordering
116 is compatible with (=) . As in the case of (=) , mutable structures are
117 compared by contents. Comparison between functional values raises
118 Invalid_argument . Comparison between cyclic structures may not termi‐
119 nate.
120 val compare : 'a -> 'a -> int
125 compare x y returns 0 if x is equal to y , a negative integer if x is
128 less than y , and a positive integer if x is greater than y . The
129 ordering implemented by compare is compatible with the comparison pred‐
130 icates = , < and > defined above, with one difference on the treatment
131 of the float value Pervasives.nan . Namely, the comparison predicates
132 treat nan as different from any other float value, including itself;
133 while compare treats nan as equal to itself and less than any other
134 float value. This treatment of nan ensures that compare defines a
135 total ordering relation.
136 compare applied to functional values may raise Invalid_argument . com‐
139 pare applied to cyclic structures may not terminate.
140 The compare function can be used as the comparison function required by
142 the Set.Make and Map.Make functors, as well as the List.sort and
143 Array.sort functions.
144 val min : 'a -> 'a -> 'a
149 Return the smaller of the two arguments. The result is unspecified if
151 one of the arguments contains the float value nan .
152 val max : 'a -> 'a -> 'a
157 Return the greater of the two arguments. The result is unspecified if
159 one of the arguments contains the float value nan .
160 val (==) : 'a -> 'a -> bool
165 e1 == e2 tests for physical equality of e1 and e2 . On mutable struc‐
168 tures, e1 == e2 is true if and only if physical modification of e1 also
169 affects e2 . On non-mutable structures, the behavior of (==) is imple‐
170 mentation-dependent; however, it is guaranteed that e1 == e2 implies
171 compare e1 e2 = 0 .
172 val (!=) : 'a -> 'a -> bool
177 Negation of Pervasives.(==) .
179 === Boolean operations ===
185 val not : bool -> bool
188 The boolean negation.
190 val (&&) : bool -> bool -> bool
195 The boolean ``and''. Evaluation is sequential, left-to-right: in e1 &&
197 e2 , e1 is evaluated first, and if it returns false , e2 is not evalu‐
198 ated at all.
199 val (&) : bool -> bool -> bool
204 Deprecated.
206 Pervasives.(&&) should be used instead.
208 val (||) : bool -> bool -> bool
213 The boolean ``or''. Evaluation is sequential, left-to-right: in e1 ||
215 e2 , e1 is evaluated first, and if it returns true , e2 is not evalu‐
216 ated at all.
217 val (or) : bool -> bool -> bool
222 Deprecated.
224 Pervasives.(||) should be used instead.
226 === Integer arithmetic ===
232 === Integers are 31 bits wide (or 63 bits on 64-bit processors). All
235 operations are taken modulo 2^{31} (or 2^{63}). They do not fail on
236 overflow. ===
237 val (~-) : int -> int
240 Unary negation. You can also write -e instead of ~-e .
242 val succ : int -> int
247 succ x is x+1 .
250 val pred : int -> int
255 pred x is x-1 .
258 val (+) : int -> int -> int
263 Integer addition.
265 val (-) : int -> int -> int
270 Integer subtraction.
272 val ( * ) : int -> int -> int
277 Integer multiplication.
279 val (/) : int -> int -> int
284 Integer division. Raise Division_by_zero if the second argument is 0.
286 Integer division rounds the real quotient of its arguments towards
287 zero. More precisely, if x >= 0 and y > 0 , x / y is the greatest
288 integer less than or equal to the real quotient of x by y . Moreover,
289 (-x) / y = x / (-y) = -(x / y) .
290 val (mod) : int -> int -> int
295 Integer remainder. If y is not zero, the result of x mod y satisfies
297 the following properties: x = (x / y) * y + x mod y and abs(x mod y) <=
298 abs(y)-1 . If y = 0 , x mod y raises Division_by_zero . Notice that x
299 mod y is nonpositive if and only if x < 0 . Raise Division_by_zero if
300 y is zero.
301 val abs : int -> int
306 Return the absolute value of the argument. Note that this may be nega‐
308 tive if the argument is min_int .
309 val max_int : int
314 The greatest representable integer.
316 val min_int : int
321 The smallest representable integer.
323 === Bitwise operations ===
329 val (land) : int -> int -> int
332 Bitwise logical and.
334 val (lor) : int -> int -> int
339 Bitwise logical or.
341 val (lxor) : int -> int -> int
346 Bitwise logical exclusive or.
348 val lnot : int -> int
353 Bitwise logical negation.
355 val (lsl) : int -> int -> int
360 n lsl m shifts n to the left by m bits. The result is unspecified if m
363 < 0 or m >= bitsize , where bitsize is 32 on a 32-bit platform and 64
364 on a 64-bit platform.
365 val (lsr) : int -> int -> int
370 n lsr m shifts n to the right by m bits. This is a logical shift:
373 zeroes are inserted regardless of the sign of n . The result is
374 unspecified if m < 0 or m >= bitsize .
375 val (asr) : int -> int -> int
380 n asr m shifts n to the right by m bits. This is an arithmetic shift:
383 the sign bit of n is replicated. The result is unspecified if m < 0 or
384 m >= bitsize .
385 === Floating-point arithmetic Caml's floating-point numbers follow the
391 IEEE 754 standard, using double precision (64 bits) numbers. Float‐
392 ing-point operations never raise an exception on overflow, underflow,
393 division by zero, etc. Instead, special IEEE numbers are returned as
394 appropriate, such as infinity for 1.0 /. 0.0, neg_infinity for -1.0 /.
395 0.0, and nan (``not a number'') for 0.0 /. 0.0. These special numbers
396 then propagate through floating-point computations as expected: for
397 instance, 1.0 /. infinity is 0.0, and any arithmetic operation with nan
398 as argument returns nan as result. ===
399 val (~-.) : float -> float
402 Unary negation. You can also write -.e instead of ~-.e .
404 val (+.) : float -> float -> float
409 Floating-point addition
411 val (-.) : float -> float -> float
416 Floating-point subtraction
418 val ( *. ) : float -> float -> float
423 Floating-point multiplication
425 val (/.) : float -> float -> float
430 Floating-point division.
432 val ( ** ) : float -> float -> float
437 Exponentiation.
439 val sqrt : float -> float
444 Square root.
446 val exp : float -> float
451 Exponential.
453 val log : float -> float
458 Natural logarithm.
460 val log10 : float -> float
465 Base 10 logarithm.
467 val cos : float -> float
472 cos a returns the cosine of angle a measured in radians.
475 val sin : float -> float
480 sin a returns the sine of angle a measured in radians.
483 val tan : float -> float
488 tan a returns the tangent of angle a measured in radians.
491 val acos : float -> float
496 acos f returns the arc cosine of f . The return angle is measured in
499 radians.
500 val asin : float -> float
505 asin f returns the arc sine of f . The return angle is measured in
508 radians.
509 val atan : float -> float
514 atan f returns the arc tangent of f . The return angle is measured in
517 radians.
518 val atan2 : float -> float -> float
523 atan2 y x returns the principal value of the arc tangent of y / x ,
526 using the signs of both arguments to determine the quadrant of the
527 result. The return angle is measured in radians.
528 val cosh : float -> float
533 cosh a returns the hyperbolic cosine of angle a measured in radians.
536 val sinh : float -> float
541 sinh a returns the hyperbolic sine of angle a measured in radians.
544 val tanh : float -> float
549 tanh f returns the hyperbolic tangent of angle a measured in radians.
552 val ceil : float -> float
557 Round the given float to an integer value. ceil f returns the least
559 integer value greater than or equal to f . See also Pervasives.floor .
560 val floor : float -> float
565 Round the given float to an integer value. floor f returns the great‐
567 est integer value less than or equal to f . See also Pervasives.ceil .
568 val abs_float : float -> float
573 abs_float f returns the absolute value of f .
576 val mod_float : float -> float -> float
581 mod_float a b returns the remainder of a with respect to b . The
584 returned value is a -. n *. b , where n is the quotient a /. b rounded
585 towards zero to an integer.
586 val frexp : float -> float * int
591 frexp f returns the pair of the significant and the exponent of f .
594 When f is zero, the significant x and the exponent n of f are equal to
595 zero. When f is non-zero, they are defined by f = x *. 2 ** n and 0.5
596 <= x < 1.0 .
597 val ldexp : float -> int -> float
602 ldexp x n returns x *. 2 ** n .
605 val modf : float -> float * float
610 modf f returns the pair of the fractional and integral part of f .
613 val float : int -> float
618 Same as Pervasives.float_of_int .
620 val float_of_int : int -> float
625 Convert an integer to floating-point.
627 val truncate : float -> int
632 Same as Pervasives.int_of_float .
634 val int_of_float : float -> int
639 Truncate the given floating-point number to an integer. The result is
641 unspecified if the argument is nan or falls outside the range of repre‐
642 sentable integers.
643 val infinity : float
648 Positive infinity.
650 val neg_infinity : float
655 Negative infinity.
657 val nan : float
662 A special floating-point value denoting the result of an undefined
664 operation such as 0.0 /. 0.0 . Stands for ``not a number''. Any
665 floating-point operation with nan as argument returns nan as result.
666 As for floating-point comparisons, = , < , <= , > and >= return false
667 and <> returns true if one or both of their arguments is nan .
668 val max_float : float
673 The largest positive finite value of type float .
675 val min_float : float
680 The smallest positive, non-zero, non-denormalized value of type float .
682 val epsilon_float : float
687 The difference between 1.0 and the smallest exactly representable
689 floating-point number greater than 1.0 .
690 type fpclass =
694 | FP_normal (* Normal number, none of the below *)
695 | FP_subnormal (* Number very close to 0.0, has reduced precision *)
696 | FP_zero (* Number is 0.0 or -0.0 *)
697 | FP_infinite (* Number is positive or negative infinity *)
698 | FP_nan (* Not a number: result of an undefined operation *)
699 The five classes of floating-point numbers, as determined by the Perva‐
702 sives.classify_float function.
703 val classify_float : float -> fpclass
708 Return the class of the given floating-point number: normal, subnormal,
710 zero, infinite, or not a number.
711 === String operations More string operations are provided in module
717 String. ===
718 val (^) : string -> string -> string
721 String concatenation.
723 === Character operations More character operations are provided in mod‐
729 ule Char. ===
730 val int_of_char : char -> int
733 Return the ASCII code of the argument.
735 val char_of_int : int -> char
740 Return the character with the given ASCII code. Raise Invalid_argument
742 char_of_int if the argument is outside the range 0--255.
743 === Unit operations ===
749 val ignore : 'a -> unit
752 Discard the value of its argument and return () . For instance,
754 ignore(f x) discards the result of the side-effecting function f . It
755 is equivalent to f x; () , except that the latter may generate a com‐
756 piler warning; writing ignore(f x) instead avoids the warning.
757 === String conversion functions ===
763 val string_of_bool : bool -> string
766 Return the string representation of a boolean.
768 val bool_of_string : string -> bool
773 Convert the given string to a boolean. Raise Invalid_argument
775 bool_of_string if the string is not true or false .
776 val string_of_int : int -> string
781 Return the string representation of an integer, in decimal.
783 val int_of_string : string -> int
788 Convert the given string to an integer. The string is read in decimal
790 (by default) or in hexadecimal (if it begins with 0x or 0X ), octal (if
791 it begins with 0o or 0O ), or binary (if it begins with 0b or 0B ).
792 Raise Failure int_of_string if the given string is not a valid repre‐
793 sentation of an integer, or if the integer represented exceeds the
794 range of integers representable in type int .
795 val string_of_float : float -> string
800 Return the string representation of a floating-point number.
802 val float_of_string : string -> float
807 Convert the given string to a float. Raise Failure float_of_string if
809 the given string is not a valid representation of a float.
810 === Pair operations ===
816 val fst : 'a * 'b -> 'a
819 Return the first component of a pair.
821 val snd : 'a * 'b -> 'b
826 Return the second component of a pair.
828 === List operations More list operations are provided in module List.
834 ===
835 val (@) : 'a list -> 'a list -> 'a list
838 List concatenation.
840 === Input/output ===
846 type in_channel
849 The type of input channel.
852 type out_channel
856 The type of output channel.
859 val stdin : in_channel
864 The standard input for the process.
866 val stdout : out_channel
871 The standard output for the process.
873 val stderr : out_channel
878 The standard error ouput for the process.
880 === Output functions on standard output ===
886 val print_char : char -> unit
889 Print a character on standard output.
891 val print_string : string -> unit
896 Print a string on standard output.
898 val print_int : int -> unit
903 Print an integer, in decimal, on standard output.
905 val print_float : float -> unit
910 Print a floating-point number, in decimal, on standard output.
912 val print_endline : string -> unit
917 Print a string, followed by a newline character, on standard output and
919 flush standard output.
920 val print_newline : unit -> unit
925 Print a newline character on standard output, and flush standard out‐
927 put. This can be used to simulate line buffering of standard output.
928 === Output functions on standard error ===
934 val prerr_char : char -> unit
937 Print a character on standard error.
939 val prerr_string : string -> unit
944 Print a string on standard error.
946 val prerr_int : int -> unit
951 Print an integer, in decimal, on standard error.
953 val prerr_float : float -> unit
958 Print a floating-point number, in decimal, on standard error.
960 val prerr_endline : string -> unit
965 Print a string, followed by a newline character on standard error and
967 flush standard error.
968 val prerr_newline : unit -> unit
973 Print a newline character on standard error, and flush standard error.
975 === Input functions on standard input ===
981 val read_line : unit -> string
984 Flush standard output, then read characters from standard input until a
986 newline character is encountered. Return the string of all characters
987 read, without the newline character at the end.
988 val read_int : unit -> int
993 Flush standard output, then read one line from standard input and con‐
995 vert it to an integer. Raise Failure int_of_string if the line read is
996 not a valid representation of an integer.
997 val read_float : unit -> float
1002 Flush standard output, then read one line from standard input and con‐
1004 vert it to a floating-point number. The result is unspecified if the
1005 line read is not a valid representation of a floating-point number.
1006 === General output functions ===
1012 type open_flag =
1015 | Open_rdonly (* open for reading. *)
1016 | Open_wronly (* open for writing. *)
1017 | Open_append (* open for appending: always write at end of file. *)
1018 | Open_creat (* create the file if it does not exist. *)
1019 | Open_trunc (* empty the file if it already exists. *)
1020 | Open_excl (* fail if Open_creat and the file already exists. *)
1021 | Open_binary (* open in binary mode (no conversion). *)
1022 | Open_text (* open in text mode (may perform conversions). *)
1023 | Open_nonblock (* open in non-blocking mode. *)
1024 Opening modes for Pervasives.open_out_gen and Pervasives.open_in_gen .
1027 val open_out : string -> out_channel
1032 Open the named file for writing, and return a new output channel on
1034 that file, positionned at the beginning of the file. The file is trun‐
1035 cated to zero length if it already exists. It is created if it does not
1036 already exists. Raise Sys_error if the file could not be opened.
1037 val open_out_bin : string -> out_channel
1042 Same as Pervasives.open_out , but the file is opened in binary mode, so
1044 that no translation takes place during writes. On operating systems
1045 that do not distinguish between text mode and binary mode, this func‐
1046 tion behaves like Pervasives.open_out .
1047 val open_out_gen : open_flag list -> int -> string -> out_channel
1052 open_out_gen mode perm filename opens the named file for writing, as
1055 described above. The extra argument mode specify the opening mode. The
1056 extra argument perm specifies the file permissions, in case the file
1057 must be created. Pervasives.open_out and Pervasives.open_out_bin are
1058 special cases of this function.
1059 val flush : out_channel -> unit
1064 Flush the buffer associated with the given output channel, performing
1066 all pending writes on that channel. Interactive programs must be care‐
1067 ful about flushing standard output and standard error at the right
1068 time.
1069 val flush_all : unit -> unit
1074 Flush all open output channels; ignore errors.
1076 val output_char : out_channel -> char -> unit
1081 Write the character on the given output channel.
1083 val output_string : out_channel -> string -> unit
1088 Write the string on the given output channel.
1090 val output : out_channel -> string -> int -> int -> unit
1095 output oc buf pos len writes len characters from string buf , starting
1098 at offset pos , to the given output channel oc . Raise Invalid_argu‐
1099 ment output if pos and len do not designate a valid substring of buf .
1100 val output_byte : out_channel -> int -> unit
1105 Write one 8-bit integer (as the single character with that code) on the
1107 given output channel. The given integer is taken modulo 256.
1108 val output_binary_int : out_channel -> int -> unit
1113 Write one integer in binary format (4 bytes, big-endian) on the given
1115 output channel. The given integer is taken modulo 2^{32. The only
1116 reliable way to read it back is through the Pervasives.input_binary_int
1117 function. The format is compatible across all machines for a given ver‐
1118 sion of Objective Caml.
1119 val output_value : out_channel -> 'a -> unit
1124 Write the representation of a structured value of any type to a chan‐
1126 nel. Circularities and sharing inside the value are detected and pre‐
1127 served. The object can be read back, by the function Perva‐
1128 sives.input_value . See the description of module Marshal for more
1129 information. Pervasives.output_value is equivalent to Marshal.to_chan‐
1130 nel with an empty list of flags.
1131 val seek_out : out_channel -> int -> unit
1136 seek_out chan pos sets the current writing position to pos for channel
1139 chan . This works only for regular files. On files of other kinds (such
1140 as terminals, pipes and sockets), the behavior is unspecified.
1141 val pos_out : out_channel -> int
1146 Return the current writing position for the given channel. Does not
1148 work on channels opened with the Open_append flag (returns unspecified
1149 results).
1150 val out_channel_length : out_channel -> int
1155 Return the size (number of characters) of the regular file on which the
1157 given channel is opened. If the channel is opened on a file that is
1158 not a regular file, the result is meaningless.
1159 val close_out : out_channel -> unit
1164 Close the given channel, flushing all buffered write operations. Out‐
1166 put functions raise a Sys_error exception when they are applied to a
1167 closed output channel, except close_out and flush , which do nothing
1168 when applied to an already closed channel. Note that close_out may
1169 raise Sys_error if the operating system signals an error when flushing
1170 or closing.
1171 val close_out_noerr : out_channel -> unit
1176 Same as close_out , but ignore all errors.
1178 val set_binary_mode_out : out_channel -> bool -> unit
1183 set_binary_mode_out oc true sets the channel oc to binary mode: no
1186 translations take place during output. set_binary_mode_out oc false
1187 sets the channel oc to text mode: depending on the operating system,
1188 some translations may take place during output. For instance, under
1189 Windows, end-of-lines will be translated from \n to \r\n . This func‐
1190 tion has no effect under operating systems that do not distinguish
1191 between text mode and binary mode.
1192 === General input functions ===
1198 val open_in : string -> in_channel
1201 Open the named file for reading, and return a new input channel on that
1203 file, positionned at the beginning of the file. Raise Sys_error if the
1204 file could not be opened.
1205 val open_in_bin : string -> in_channel
1210 Same as Pervasives.open_in , but the file is opened in binary mode, so
1212 that no translation takes place during reads. On operating systems that
1213 do not distinguish between text mode and binary mode, this function
1214 behaves like Pervasives.open_in .
1215 val open_in_gen : open_flag list -> int -> string -> in_channel
1220 open_in_gen mode perm filename opens the named file for reading, as
1223 described above. The extra arguments mode and perm specify the opening
1224 mode and file permissions. Pervasives.open_in and Perva‐
1225 sives.open_in_bin are special cases of this function.
1226 val input_char : in_channel -> char
1231 Read one character from the given input channel. Raise End_of_file if
1233 there are no more characters to read.
1234 val input_line : in_channel -> string
1239 Read characters from the given input channel, until a newline character
1241 is encountered. Return the string of all characters read, without the
1242 newline character at the end. Raise End_of_file if the end of the file
1243 is reached at the beginning of line.
1244 val input : in_channel -> string -> int -> int -> int
1249 input ic buf pos len reads up to len characters from the given channel
1252 ic , storing them in string buf , starting at character number pos .
1253 It returns the actual number of characters read, between 0 and len
1254 (inclusive). A return value of 0 means that the end of file was
1255 reached. A return value between 0 and len exclusive means that not all
1256 requested len characters were read, either because no more characters
1257 were available at that time, or because the implementation found it
1258 convenient to do a partial read; input must be called again to read the
1259 remaining characters, if desired. (See also Pervasives.really_input
1260 for reading exactly len characters.) Exception Invalid_argument input
1261 is raised if pos and len do not designate a valid substring of buf .
1262 val really_input : in_channel -> string -> int -> int -> unit
1267 really_input ic buf pos len reads len characters from channel ic ,
1270 storing them in string buf , starting at character number pos . Raise
1271 End_of_file if the end of file is reached before len characters have
1272 been read. Raise Invalid_argument really_input if pos and len do not
1273 designate a valid substring of buf .
1274 val input_byte : in_channel -> int
1279 Same as Pervasives.input_char , but return the 8-bit integer represent‐
1281 ing the character. Raise End_of_file if an end of file was reached.
1282 val input_binary_int : in_channel -> int
1287 Read an integer encoded in binary format (4 bytes, big-endian) from the
1289 given input channel. See Pervasives.output_binary_int . Raise
1290 End_of_file if an end of file was reached while reading the integer.
1291 val input_value : in_channel -> 'a
1296 Read the representation of a structured value, as produced by Perva‐
1298 sives.output_value , and return the corresponding value. This function
1299 is identical to Marshal.from_channel ; see the description of module
1300 Marshal for more information, in particular concerning the lack of type
1301 safety.
1302 val seek_in : in_channel -> int -> unit
1307 seek_in chan pos sets the current reading position to pos for channel
1310 chan . This works only for regular files. On files of other kinds, the
1311 behavior is unspecified.
1312 val pos_in : in_channel -> int
1317 Return the current reading position for the given channel.
1319 val in_channel_length : in_channel -> int
1324 Return the size (number of characters) of the regular file on which the
1326 given channel is opened. If the channel is opened on a file that is
1327 not a regular file, the result is meaningless. The returned size does
1328 not take into account the end-of-line translations that can be per‐
1329 formed when reading from a channel opened in text mode.
1330 val close_in : in_channel -> unit
1335 Close the given channel. Input functions raise a Sys_error exception
1337 when they are applied to a closed input channel, except close_in ,
1338 which does nothing when applied to an already closed channel. Note
1339 that close_in may raise Sys_error if the operating system signals an
1340 error.
1341 val close_in_noerr : in_channel -> unit
1346 Same as close_in , but ignore all errors.
1348 val set_binary_mode_in : in_channel -> bool -> unit
1353 set_binary_mode_in ic true sets the channel ic to binary mode: no
1356 translations take place during input. set_binary_mode_out ic false
1357 sets the channel ic to text mode: depending on the operating system,
1358 some translations may take place during input. For instance, under
1359 Windows, end-of-lines will be translated from \r\n to \n . This func‐
1360 tion has no effect under operating systems that do not distinguish
1361 between text mode and binary mode.
1362 === Operations on large files ===
1368 module LargeFile : sig end
1371 Operations on large files. This sub-module provides 64-bit variants of
1374 the channel functions that manipulate file positions and file sizes.
1375 By representing positions and sizes by 64-bit integers (type int64 )
1376 instead of regular integers (type int ), these alternate functions
1377 allow operating on files whose sizes are greater than max_int .
1378 === References ===
1384 type 'a ref = {
1387 mutable contents : 'a ;
1389 }
1390 The type of references (mutable indirection cells) containing a value
1393 of type 'a .
1394 val ref : 'a -> 'a ref
1399 Return a fresh reference containing the given value.
1401 val (!) : 'a ref -> 'a
1406 !r returns the current contents of reference r . Equivalent to fun r
1409 -> r.contents .
1410 val (:=) : 'a ref -> 'a -> unit
1415 r := a stores the value of a in reference r . Equivalent to fun r v ->
1418 r.contents <- v .
1419 val incr : int ref -> unit
1424 Increment the integer contained in the given reference. Equivalent to
1426 fun r -> r := succ !r .
1427 val decr : int ref -> unit
1432 Decrement the integer contained in the given reference. Equivalent to
1434 fun r -> r := pred !r .
1435 === Operations on format strings ===
1441 === Format strings are used to read and print data using formatted
1444 input functions in module Scanf and formatted output in modules Printf
1445 and Format. ===
1446 type ('a, 'b, 'c, 'd) format4 = ('a, 'b, 'c, 'c, 'c, 'd) format6
1449 Format strings have a general and highly polymorphic type ('a, 'b, 'c,
1452 'd, 'e, 'f) format6 . Type format6 is built in. The two simplified
1453 types, format and format4 below are included for backward compatibility
1454 with earlier releases of Objective Caml. 'a is the type of the parame‐
1455 ters of the format, 'c is the result type for the "printf"-style func‐
1456 tion, and 'b is the type of the first argument given to %a and %t
1457 printing functions.
1458 type ('a, 'b, 'c) format = ('a, 'b, 'c, 'c) format4
1462 val string_of_format : ('a, 'b, 'c, 'd, 'e, 'f) format6 -> string
1468 Converts a format string into a string.
1470 val format_of_string : ('a, 'b, 'c, 'd, 'e, 'f) format6 -> ('a, 'b, 'c,
1475 'd, 'e, 'f) format6
1476 format_of_string s returns a format string read from the string literal
1479 s .
1480 val (^^) : ('a, 'b, 'c, 'd, 'e, 'f) format6 -> ('f, 'b, 'c, 'e, 'g, 'h)
1485 format6 -> ('a, 'b, 'c, 'd, 'g, 'h) format6
1486 f1 ^^ f2 catenates formats f1 and f2 . The result is a format that
1489 accepts arguments from f1 , then arguments from f2 .
1490 === Program termination ===
1496 val exit : int -> 'a
1499 Terminate the process, returning the given status code to the operating
1501 system: usually 0 to indicate no errors, and a small positive integer
1502 to indicate failure. All open output channels are flushed with
1503 flush_all. An implicit exit 0 is performed each time a program termi‐
1504 nates normally. An implicit exit 2 is performed if the program termi‐
1505 nates early because of an uncaught exception.
1506 val at_exit : (unit -> unit) -> unit
1511 Register the given function to be called at program termination time.
1513 The functions registered with at_exit will be called when the program
1514 executes Pervasives.exit , or terminates, either normally or because of
1515 an uncaught exception. The functions are called in ``last in, first
1516 out'' order: the function most recently added with at_exit is called
1517 first.
1518OCamldoc 2017-03-22 Pervasives(3)